gzserver error: Exception [RenderEngine.cc:645] unable to find OpenGL rendering system

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I'm getting the following error every time I run gzserver or when I try to launch a simulator using roslaunch. I'm not able to find any thing wrong in OGRE installation/configuration

Please let me know what is wrong?

mkhuthir@MuthPC:~$ gzserver
Gazebo multi-robot simulator, version 2.2.6
Copyright (C) 2012-2014 Open Source Robotics Foundation.
Released under the Apache 2 License.
http://gazebosim.org
Msg Waiting for master
Msg Connected to gazebo master @ http://127.0.0.1:11345
Msg Publicized address: 192.168.1.117
Exception [RenderEngine.cc:645] unable to find OpenGL rendering system. 
OGRE is probably installed incorrectly. Double check the OGRE cmake 
output, and make sure OpenGL is enabled.
Error [RenderingIface.cc:38] Failed to load the Rendering engine subsystem
unable to find OpenGL rendering system. OGRE is probably installed 
incorrectly. Double check the OGRE cmake output, and make sure OpenGL is 
enabled.
Error [gazebo.cc:179] Unable to load sensors
Error [Server.cc:212] Unable to load gazebo